It's the most mysterious manner of infant mortality, and most common, but it may also be among the most preventable.

Sudden infant death syndrome took the lives of 0.22 babies per 1,000 live births in New Jersey from 2012 to 2014, according to U.S. Centers for Disease Control statistics. A baby who appears healthy one minute may be found deceased by the time they wake up, and the death can not be explained after a thorough and complete investigation.

Instances of SIDS, now considered one of three categories under the umbrella of sudden unexpected infant death, have decreased significantly over the years due to public education and awareness campaigns. It was responsible for the deaths of 0.47 babies per 1,000 live births in New Jersey from 1995 to 1997.

SIDS rates declined nationally from 130.3 deaths per 100,000 live births in 1990 to 39.4 deaths per 100,000 live births in 2015, according to the CDC.

When considering all three categories under SUID — sudden infant death syndrome, accidental suffocation and strangulation in bed, and unknown causes due to to an incomplete investigation — New Jersey boasts the lowest rate in the nation along with California. New Jersey's averaged SUID rate for 2012 to 2014 was 0.48 per 1,000 live births, compared to 0.87 nationally.

"We don't smile at the decline, I assure you," said Barbara Ostfeld, program director for the SIDS Center of New Jersey at Rutgers Robert Wood Johnson Medical School. "It's a moment of joy and then back to sadness because babies are still dying."

SIDS is the leading cause of death among infants between 1 and 12 months old.

SUID and SIDS rates saw a considerable decline following the release of the American Academy of Pediatrics recommendations in 1992 and the launch of the Back to Sleep campaign in 1994.

While there's no definitive explanation for death in a SIDS case, according to Ostfeld, there are definitive risk factors that elevate the likelihood of these deaths — such as the way a child is put to sleep and his/her surroundings — and it is "very rare" to have a SIDS death in the absence of these risk factors.

"Not every death is preventable, but so many of these deaths can be helped to be diminished with the application of safe sleep," Ostfeld said.

The postcard above details the SIDS Center's safe sleep recommendations, based on guidelines from the American Academy of Pediatrics. They include placing a baby on its back and keeping the crib free of clutter, including bumpers. Ostfeld notes the city of Watchung has banned the sale of bumpers, along with Chicago and Maryland.

Ostfeld said three-quarters of America's babies were put to sleep on their bellies in 1992. By the year 2000, 75 percent were put to sleep on their backs.

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Contact reporter Dino Flammia at dino.flammia@townsquaremedia.com.